Set Appliance State:

Mains Power Off
Ensure no demands
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow boiler 90 seconds to complete its self check.
Pump will pulse briefly but should otherwise not run.
Fan may run for approximately 10 seconds, if it runs continually select that option below.
If a fault code is shown at any point choose that option and use the fault code diagnostics.